unlock a built-in variable you
			will get an error message "E940: Cannot lock or unlock
			variable {name}".

			[depth] is relevant when locking a |List| or
			|Dictionary|.  It specifies how deep the locking goes:
				0	Lock the variable {name} but not its
					value.
				1	Lock the |List| or |Dictionary| itself,
					cannot add or remove items, but can
					still change their values.
				2	Also lock the values, cannot change
					the items.  If an item is a |List| or
					|Dictionary|, cannot add or remove
					items, but can still change the
					values.
				3	Like 2 but for the |List| /
					|Dictionary| in the |List| /
					|Dictionary|, one level deeper.
			The default [depth] is 2, thus when {name} is a |List|
			or |Dictionary| the values cannot be changed.

			Example with [depth] 0: >
				let mylist = [1, 2, 3]
				lockvar 0 mylist
				let mylist[0] = 77	" OK
				call add(mylist, 4)	" OK
				let mylist = [7, 8, 9]  " Error!
<								*E743*
			For unlimited depth use [!] and omit [depth].
			However, there is a maximum depth of 100 to catch
			loops.

			Note that when two variables refer to the same |List|
			and you lock one of them, the |List| will also be
			locked when used through the other variable.
			Example: >
				:let l = [0, 1, 2, 3]
				:let cl = l
				:lockvar l
				:let cl[1] = 99		" won't work!
<			You may want to make a copy of a list to avoid this.
			See |deepcopy()|.


:unlo[ckvar][!] [depth] {name} ...			*:unlockvar* *:unlo*
			Unlock the internal variable {name}.  Does the
			opposite of |:lockvar|.

			No error is given if {name} does not exist.

:if {expr1}			*:if* *:end* *:endif* *:en* *E171* *E579* *E580*
:en[dif]		Execute the commands until the next matching `:else`
			or `:endif` if {expr1} evaluates to non-zero.
			Although the short forms work, it is recommended to
			always use `:endif` to avoid confusion and to make
			auto-indenting work properly.

			From Vim version 4.5 until 5.0, every Ex command in
			between the `:if` and `:endif` is ignored.  These two
			commands were just to allow for future expansions in a
			backward compatible way.  Nesting was allowed.  Note
			that any `:else` or `:elseif` was ignored, the `else`
			part was not executed either.

			You can use this to remain compatible with older
			versions: >
				:if version >= 500
				:  version-5-specific-commands
				:endif
<			The commands still need to be parsed to find the
			`endif`.  Sometimes an older Vim has a problem with a
			new command.  For example, `:silent` is recognized as
			a `:substitute` command.  In that case `:execute` can
			avoid problems: >
				:if version >= 600
				:  execute "silent 1,$delete"
				:endif
<
			NOTE: The `:append` and `:insert` commands don't work
			properly in between `:if` and `:endif`.

						*:else* *:el* *E581* *E583*
:el[se]			Execute the commands until the next matching `:else`
			or `:endif` if they previously were not being
			executed.

					*:elseif* *:elsei* *E582* *E584*
:elsei[f] {expr1}	Short for `:else` `:if`, with the addition that there
			is no extra `:endif`.

:wh[ile] {expr1}			*:while* *:endwhile* *:wh* *:endw*
						*E170* *E585* *E588* *E733*
:endw[hile]		Repeat the commands between `:while` and `:endwhile`,
			as long as {expr1} evaluates to non-zero.
			When an error is detected from a command inside the
			loop, execution continues after the `endwhile`.
			Example: >
				:let lnum = 1
				:while lnum <= line("$")
				   :call FixLine(lnum)
				   :let lnum = lnum + 1
				:endwhile
<
			NOTE: The `:append` and `:insert` commands don't work
			properly inside a `:while` and `:for` loop.

:for {var} in {object}					*:for* *E690* *E732*
:endfo[r]						*:endfo* *:endfor*
			Repeat the commands between `:for` and `:endfor` for
			each item in {object}.  {object} can be a |List|,
			a |Blob| or a |String|.

			Variable {var} is set to the value of each item.

			When an error is detected for a command inside the
			loop, execution continues after the `endfor`.